That’s a bad apples-to-oranges comparison, unique_ptr frees memory upon destruction, which with the raw pointer version you don’t do. The least you could do is use rvalue references. The class layout of unique_ptr is also hard to optimize away (unless via LTO) because consume isn’t in the same translation unit and the compiler has to let your binary be ABI compatible with the rest of your binaries. (Also, you’re using Clang 9 by the way, we are at version 17 now)

This is much fairer: https://godbolt.org/z/v4PYcd8hf

Then, if you additionally make the functions’ bodies accessible to the compiler and add a free to the raw pointer version (for fairness if you insist to have consume or foo destroy the resource), you should get an almost identical assembly code (with still an extra indirection that you’ll see in an extra mov due to the fact that the C++ compiler still doesn’t see how you use them, but IMO that should still be a textbook case for LTO), and the non-zero difference should disappear altogether once you actually use those functions and if it doesn’t you absolutely should file a bug report.

Carruth, while an excellent presenter, has been on a “C++ standard committee bad, why don’t we do more ABI-breaking changes, y’all suck, Abseil and Carbon rule” rant spree, with that basically materialized by Google stopping active participation in Clang (haven’t followed the drama since then so not sure if Google backtracked on that decision), and it’s hard to consider him to be objective about this since he also has the Carbon project and his recent Carbon talks are painful to watch as it’s hard to ignore how he’s going from a “C++ optimization chad” that he used to be to a Google marketing/sales person.